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4ct Ruby (Round, 9.49×9.49mm, Red) vs 1ct Diamond (Round, 6.5×6.5mm, White)


Quick summary: When looked from above (face-up position), 4ct Ruby (9.49×9.49mm, round cut) appears 2.1 times larger than 1ct Diamond (6.5×6.5mm, round cut). See below how they compare side-by-side on a ring and finger.

4ct Ruby (round cut)
vs
 1ct Diamond (round cut)
red
 
white
9.49×9.49 mm 6.5×6.5 mm
actual size
Actual size of 4ct Ruby (round cut, 9.49×9.49mm, Red color)   Actual size of 1ct Diamond (round cut, 6.5×6.5mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Red 4ct Ruby (round cut, 9.49×9.49mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 1ct Diamond (round cut, 6.5×6.5mm) on a right ring and finger
Your settings
Ring
 Gold
Skin tone
 Light
Ring diameter
 16.9 mm
Ring width
 3.0 mm
Finger length
 64 mm
Finger coverage
 57% vs 39%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 4ct Ruby Round (9.49×9.49mm, Red) and 1ct Diamond Round (6.5×6.5mm, White) as they would appear on a ring and finger. Adjust the ring and finger size to get an idea of how these gemstones would look on your finger.

Where to buy?

For certified gemstones, high-end gemstone jewelry, and birthstone jewelry, see Blue Nile

Face-up Size

All things being equal, Ruby will face-up smaller than Diamond for a given carat weight, because it has higher specific gravity (4 vs. 3.52 - this means it's "heavier" compared to Diamond of the same size). Face-up size also depends heavily on the proportions of the cut.

Face-up area is a measure of the size of the gem when viewed from above (as set in a ring). It tells you how big the gem is at the girdle plane.


4 Ct Ruby (Round) 1 Ct Diamond (Round)
9.49×9.49 mm vs 6.5×6.5 mm
70.73 mm²   33.18 mm²
Face-up size outline for 4ct Ruby (9.49×9.49mm, round cut)
Face-up size outline for 1ct Diamond (6.5×6.5mm, round cut)
4ct Ruby Round (9.49×9.49mm)
1ct Diamond Round (6.5×6.5mm)
Difference: 113% (37.55 mm²)
4ct Ruby (Round, 9.49×9.49mm) has approx. 113% more face-up area than 1ct Diamond (Round, 6.5×6.5mm). In other words, it's 2.13x larger.


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